Somehow, iodine has passed through the wall into the plastic bag, but the cornstarch was not able to pass into the iodine. Cornstarch molecules are large, compared to those of iodine. ), so they can pass through. However, the holes are too small to allow cornstarch molecules to pass so they are held inside the bag. Thus the iodine mixture remains its original color. Fun Facts Diffusion and osmosis are two ways cells can get the nutrients they need to grow and be healthy. osmosis: a process in which liquids pass through the walls of cells.

Org . TRY THIS FALLING LEAVES Some trees stay green the whole year round while others lose their leaves in the fall and winter and grow new leaves in the spring. If you’ve ever seen trees lose their leaves in the fall, you may have noticed that the leaves turn from green to yellow, red, or orange before eventually falling to the ground. QUESTION Where do the leaves get their colors? MATERIALS 4–5 spinach leaves 1 drinking glass Spoon Nail polish remover — ask a parent for help in getting this Coffee filter Scissors Tape Pencil PROCEDURE Tear the leaves into small pieces.

MATERIALS Cabbage indicator — the liquid from a jar of pickled red cabbage, available at the grocery store Eyedropper 1 small plate for each of the materials you wish to test. Below are some samples: Lemon juice Orange juice Baking soda Vinegar Antacid tablet Tea bag — mix with water to make tea Ground coffee indicator: a liquid (like the juice of a red cabbage) that tells you if something is an acid or a base. PROCEDURE Pour some of the indicator into several small plates. Drop a small amount of each test item onto a plate and watch what happens to the indicator.